This application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2005-28064 filed in Japan on Feb. 3, 2005, the entire contents of which are hereby incorporated by reference.
The present invention relates to an image forming apparatus provided with a paper post-processing portion.
In recent years, as image forming apparatuses come to have multiple functions, development of paper post-processing apparatuses that perform post-processing for printed paper has been advancing. Examples of functions of such paper post-processing apparatuses include a staple function, a hole-punching function, and a binding function. However, a processing mechanism for any paper post-processing apparatus having such functions has been enlarged. Thus, when a compact image forming apparatus is provided with a paper post-processing apparatus, it is necessary to dispose the paper post-processing apparatus outside the image forming apparatus.
Disposing the paper post-processing apparatus outside the image forming apparatus in this manner leads to the problem not only that the area occupied by the apparatus as a whole increases but also that the electric power consumption of the apparatus as a whole increases. For example, with an electrical wiring specification generally adopted in Japan (outlet wiring: 100V, 15A), there is the possibility that the rated electric power is exceeded. In this case, the trouble is caused that it is necessary to separately wire the image forming apparatus and the paper post-processing apparatus.
Thus, a technique has been proposed in which a paper post-processing apparatus itself is designed so as to be compact, and the paper post-processing apparatus is disposed within a space formed in an image forming apparatus instead of disposing it outside the image forming apparatus (see JP 2003-335449A, for example). More specifically, the paper post-processing apparatus is disposed using a space formed by an original reading portion, a printing portion, and a paper-feed portion in order to solve the above-described problems.
On the other hand, in the image forming apparatus provided with such a conventional paper post-processing apparatus as described above, a configuration is adopted in which a discharge tray portion that can be extended or retracted is disposed on the downstream side of the paper post-processing apparatus, and the discharge tray portion is used as a paper holding portion for staple processing when staple processing is performed with the paper post-processing apparatus.
Furthermore, with this retractable discharge tray portion, unless the discharge tray portion is used in an extended state, discharged paper cannot be placed on the discharge tray portion and the paper falls from the discharge tray portion, depending on the types (large size such as B4 and A3, for example) of paper to be discharged. More specifically, when staple processing is performed for paper of a large size, if the discharge tray portion is retracted, then the problem is caused not only that paper falls but also that the staple processing cannot be performed.